Fuel dyes
Fuel dyes are dyes added to fuels, as in some countries it is required by law to dye a low-tax fuel to deter its use in applications intended for higher-taxed ones. Untaxed fuels are referred to as "dyed", while taxed ones are called "clear" or "white". The dyes used have to be soluble in the fuels they are added to and therefore in hydrocarbon-based nonpolar solvents ("solvent dyes"). Red dyes are often various diazo dyes, e.g. Solvent Red 19, Solvent Red 24, and Solvent Red 26. Anthraquinone dyes are used for green and blue shades, e.g. Solvent Green 33, Solvent Blue 35 and Solvent Blue 26. It is advantageous to mix a liquid with a liquid instead of handling powdered dyes into a liquid. The pure dyes found in modern liquid petroleum dyes are essentially longer alkyl side chain forms of traditional dyes and normally multiple chain length variations of the chromophore are found within a typical commercial liquid petroleum dye. For instance, Sudan Red 462 is essentially Solvent Red 19, with the ethyl side chain replaced by either a 2-ethylhexyl or a tridecyl side chain. The longer branched side chains improve solubility dramatically, but in some cases the high solubility prevents the dye being isolated as a crystal, except at very low temperatures. The high solubility liquid dyes originated with Morton International and BASF (ACNA Italy) as the primary inventors. For instance, Morton International created Solvent Blue 98 as a high solubility form of Solvent Blue 35. BASF created Solvent Blue 79 as its high solubility form of Solvent Blue 35. In some cases it is possible, with normal solvents - e.g. xylene - to prepare stable (to -20C) solutions at 65% "solids" content. The original powder dye form of the chromophore would not be soluble beyond 2% in xylene. Only a few refineries worldwide still use powder dyes for colouring fuels, as ultimately they are still lower cost per active molecule of dye chromphore than the modified forms. They have significant handling issues and health and safety issues that inherently arise from the handling of azo dyes (reds/yellows/green mixes). Aviation gasoline is dyed, both for tax reasons (avgas is typically taxed to support aviation infrastructure) as well as safety (due to the consequences of fueling an aircraft with the wrong kind of fuel). Fuel dye in the European Union After August 2002, all European Union countries became obliged to add about 6 mg/L of Solvent Yellow 124, a dye with structure similar to Solvent Yellow 56, to all motor diesel fuel. This dye can be easily hydrolyzed with acids, splitting off the acetal group responsible for its solubility in nonpolar solvents, and yielding a water-soluble form. Like a similar methyl orange dye, it changes color to red in acidic pH. It can be easily detected in the fuel at levels as low as 0.3 ppm by extraction to a diluted hydrochloric acid, allowing detection of the red diesel added into motor diesel in amounts as low as 2-3%. United Kingdom In the United Kingdom, "red diesel" is dyed gas oil for registered agricultural or construction vehicles such as tractors, excavators, cranes and some other non-road applications such as boats. Red diesel carries a significantly reduced tax levy compared to un-dyed diesel fuel used in ordinary road vehicles. As red diesel is widely available in the UK, the authorities regularly carry out roadside checks, highly unlikely in a metropolitan area but much more likely in a rural area. Unauthorized use incurs heavy fines and/or confication of the vehicle, but despite this spot checks have occasionally found as many as one in five motorists using red diesel. Red diesel can also be used in road vehicles which are registered as SORN with the DVLA provided they are only used on private land. There is also no need to tax a vehicle that is not used on a public road. Carbon Offset Red Diesel Carbon Offset Red Diesel is now available in the UK. It is an environmentally friendly alternative to regular red diesel. There is an extra cost incurred when purchasing Carbon Offset Red Diesel, however some suppliers of the fuel are donating the extra cost to projects aimed at lowering carbon emissions, meaning they make no extra profit from the sale of Carbon Offset Red Diesel.http://www.red-diesel-deliveries.co.uk Poland Currently there are no naked-eye visible dyes in car fuels sold in Poland. However, during the time of the communism, the state-owned CPN fuel monopoly was dying leaded gasolines (marketed as "ethilins") in following colors: 78 - blue, 86 - green, 94 - yellow, 98 - red. Diesel fuel, although unleaded, was also dyed in brown color. Fuel dye in North America In United States of America, the Environmental Protection Agency mandates use of a red dye to identify high-sulfur fuels for off-road use. Solvent Red 26 is used in the United States as a standard, though it is often replaced with Solvent Red 164, which is similar to Solvent Red 26 but with longer alkyl chains. The Internal Revenue Service regulation mandates use of the same red dyes, in fivefold concentration, for tax-exempt diesel fuels such as heating oil; their argument for the higher dye content is to allow detection even when diluted with "legal" fuel. Detection of red-dyed fuel in the fuel system of an on-road vehicle will incur substantial penalties. Blue dyes are used for diesel designated for governmental and institutional vehicles, to detect theft. Fuel laundering Processing fuel to remove the dye so it may be illicitly sold to motorists is a recognized criminal activity in Ireland and the United Kingdom. In Northern Ireland and the Republic of Ireland it has been a means of fund raising by illegal paramilitary organizations. In 2004, Northern Irish police discovered an illegal facility capable of removing the dye from 12 million litres of fuel per year. In 2009, customs officials shut down a plant capable of removing the dye from 6.5 million litres of fuel per year. In 2011, a plant capable of processing 30m litres was discovered. Dyes used Some dyes required in some countries are listed here: References External links * Minnesota State Patrol Commercial Vehicle Enforcement Dyed Fuel Program * Shell information on aviation gasoline specifications Category:Fuel production Category:Fuel dyes